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@snmishra
Last active May 26, 2023 13:07
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What would you like to do?
Short python script to read ngspice raw binary files
# MIT license: https://opensource.org/licenses/MIT
# See https://github.com/Isotel/mixedsim/blob/master/python/ngspice_read.py
# for a more complete library. Isotel's version is GPL licensed
from __future__ import division
import numpy as np
BSIZE_SP = 512 # Max size of a line of data; we don't want to read the
# whole file to find a line, in case file does not have
# expected structure.
MDATA_LIST = [b'title', b'date', b'plotname', b'flags', b'no. variables',
b'no. points', b'dimensions', b'command', b'option']
def rawread(fname: str):
"""Read ngspice binary raw files. Return tuple of the data, and the
plot metadata. The dtype of the data contains field names. This is
not very robust yet, and only supports ngspice.
>>> darr, mdata = rawread('test.py')
>>> darr.dtype.names
>>> plot(np.real(darr['frequency']), np.abs(darr['v(out)']))
"""
# Example header of raw file
# Title: rc band pass example circuit
# Date: Sun Feb 21 11:29:14 2016
# Plotname: AC Analysis
# Flags: complex
# No. Variables: 3
# No. Points: 41
# Variables:
# 0 frequency frequency grid=3
# 1 v(out) voltage
# 2 v(in) voltage
# Binary:
fp = open(fname, 'rb')
plot = {}
count = 0
arrs = []
plots = []
while (True):
try:
mdata = fp.readline(BSIZE_SP).split(b':', maxsplit=1)
except:
raise
if len(mdata) == 2:
if mdata[0].lower() in MDATA_LIST:
plot[mdata[0].lower()] = mdata[1].strip()
if mdata[0].lower() == b'variables':
nvars = int(plot[b'no. variables'])
npoints = int(plot[b'no. points'])
plot['varnames'] = []
plot['varunits'] = []
for varn in range(nvars):
varspec = (fp.readline(BSIZE_SP).strip()
.decode('ascii').split())
assert(varn == int(varspec[0]))
plot['varnames'].append(varspec[1])
plot['varunits'].append(varspec[2])
if mdata[0].lower() == b'binary':
rowdtype = np.dtype({'names': plot['varnames'],
'formats': [np.complex_ if b'complex'
in plot[b'flags']
else np.float_]*nvars})
# We should have all the metadata by now
arrs.append(np.fromfile(fp, dtype=rowdtype, count=npoints))
plots.append(plot)
fp.readline() # Read to the end of line
else:
break
return (arrs, plots)
if __name__ == '__main__':
arrs, plots = rawread('test.raw')
print(arrs)
# Local Variables:
# mode: python
# End:
@cardosorapha
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Works really well out of the box. Thank you very much!

@snmishra
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Thanks @cardosorapha

@hacksterous
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hacksterous commented May 26, 2023

For plotting, I needed a small change --

"""Read ngspice binary raw files. Return tuple of the data, and the
plot metadata. The dtype of the data contains field names. This is
not very robust yet, and only supports ngspice.
>>> darr, mdata = rawread('test.py')
>>> darr.dtype.names
>>> plot(np.real(darr[0]['frequency']), np.abs(darr[0]['v(out)']))
"""

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